/*
 * Copyright (c) 2004, National ICT Australia
 */
/*
 * Copyright (c) 2007 Open Kernel Labs, Inc. (Copyright Holder).
 * All rights reserved.
 *
 * 1. Redistribution and use of OKL4 (Software) in source and binary
 * forms, with or without modification, are permitted provided that the
 * following conditions are met:
 *
 *     (a) Redistributions of source code must retain this clause 1
 *         (including paragraphs (a), (b) and (c)), clause 2 and clause 3
 *         (Licence Terms) and the above copyright notice.
 *
 *     (b) Redistributions in binary form must reproduce the above
 *         copyright notice and the Licence Terms in the documentation and/or
 *         other materials provided with the distribution.
 *
 *     (c) Redistributions in any form must be accompanied by information on
 *         how to obtain complete source code for:
 *        (i) the Software; and
 *        (ii) all accompanying software that uses (or is intended to
 *        use) the Software whether directly or indirectly.  Such source
 *        code must:
 *        (iii) either be included in the distribution or be available
 *        for no more than the cost of distribution plus a nominal fee;
 *        and
 *        (iv) be licensed by each relevant holder of copyright under
 *        either the Licence Terms (with an appropriate copyright notice)
 *        or the terms of a licence which is approved by the Open Source
 *        Initative.  For an executable file, "complete source code"
 *        means the source code for all modules it contains and includes
 *        associated build and other files reasonably required to produce
 *        the executable.
 *
 * 2. THIS SOFTWARE IS PROVIDED ``AS IS'' AND, TO THE EXTENT PERMITTED BY
 * LAW, ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
 * PURPOSE, OR NON-INFRINGEMENT, ARE DISCLAIMED.  WHERE ANY WARRANTY IS
 * IMPLIED AND IS PREVENTED BY LAW FROM BEING DISCLAIMED THEN TO THE
 * EXTENT PERMISSIBLE BY LAW: (A) THE WARRANTY IS READ DOWN IN FAVOUR OF
 * THE COPYRIGHT HOLDER (AND, IN THE CASE OF A PARTICIPANT, THAT
 * PARTICIPANT) AND (B) ANY LIMITATIONS PERMITTED BY LAW (INCLUDING AS TO
 * THE EXTENT OF THE WARRANTY AND THE REMEDIES AVAILABLE IN THE EVENT OF
 * BREACH) ARE DEEMED PART OF THIS LICENCE IN A FORM MOST FAVOURABLE TO
 * THE COPYRIGHT HOLDER (AND, IN THE CASE OF A PARTICIPANT, THAT
 * PARTICIPANT). IN THE LICENCE TERMS, "PARTICIPANT" INCLUDES EVERY
 * PERSON WHO HAS CONTRIBUTED TO THE SOFTWARE OR WHO HAS BEEN INVOLVED IN
 * THE DISTRIBUTION OR DISSEMINATION OF THE SOFTWARE.
 *
 * 3. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR ANY OTHER PARTICIPANT BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
 * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
 * IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/*
 * Author: Carlos Dyonisio <medaglia@ok-labs.com>
 */

#include <stdio.h>
#include <stdlib.h>
#include <time.h>

#include "libtime.h"

static struct tm __gmtime_result;

struct tm *
gmtime(const time_t *timer)
{
    return gmtime_r(timer, &__gmtime_result);
}

struct tm *
gmtime_r(const time_t *timer, struct tm *res)
{
    long unix_days; /* days since Unix Epoch */
    int unix_years; /* years since Unix Epoch */
    long year_days;
    long year_sec;
    int year_month;
    int month_days;
    int day_sec;

    unix_days = *timer / 86400;

    year_days = unix_days;
    unix_years = get_unix_years(&year_days);

    year_sec = (year_days * 86400) + (*timer % 86400);
    if (year_sec < 0) {
        if (is_leap_year(1970 + unix_years)) {
            year_sec = (86400 * 366) + year_sec;
        } else {
            year_sec = (86400 * 365) + year_sec;
        }
        year_days = year_sec / 86400;
    }

    month_days = year_days;
    year_month = get_year_month(&month_days, is_leap_year(1970 + unix_years));

    day_sec = year_sec % 86400;

    res->tm_hour = day_sec / 3600;
    res->tm_min = (day_sec % 3600) / 60;
    res->tm_sec = (day_sec % 3600) % 60;
    
    res->tm_mday = month_days;
    res->tm_mon = year_month;
    res->tm_year = (1970 + unix_years) - 1900;

    res->tm_wday = get_week_day(unix_days);
    res->tm_yday = year_days;
    res->tm_isdst = daylight;

    /*
     * This function (and localtime) must set errno to EOVERFLOW if the
     * result can't be represented. I think it never happens. (CD)
     */

    return res;
}
